1. Field of the Invention
The present invention relates to a method for incubating, in particular pre-incubating, eggs, in which use is made of an incubating device, comprising:                a cabinet provided with a climate control for controlling the atmospheric humidity and temperature of air that is to be passed through the cabinet; and        at least one frame, in which there is arranged at least one stack of trays placed vertically above one another, each tray comprising a multiplicity of egg positions, in each of which an egg can be received, the trays of the stack being pivotable back and forth through a defined pivot angle about a horizontal axis with respect to the frame, in order to turn the eggs, in such a manner that the vertical distance between trays located above one another is dependent on the angle position of the said trays with respect to the horizontal plane;the trays being periodically pivoted through the said defined pivot angle, while the frame with eggs positioned in the egg positions is located in the cabinet and the climate in the cabinet is being controlled by the climate control.        
The invention also relates to an incubation device for the incubation, in particular. preincubation, of eggs, comprising:                a cabinet provided with a climate control for controlling the atmospheric humidity and temperature of air that is to be passed through the cabinet; and        at least one frame, in which there is arranged at least one stack of trays placed vertically above one another, each tray comprising a multiplicity of egg positions, in each of which an egg can be received, the trays of the stack being pivotable back and forth through a defined pivot angle about a horizontal axis with respect to the frame, in order to turn the eggs, in such a manner that the vertical distance between trays located above one another is dependent on the angle position of the said trays with respect to the horizontal plane;        pivot means for each stack for periodically pivoting the trays through the defined pivot angle.        
2. Description of the Related Art
It is generally known to incubate eggs in incubation devices, which substantially comprise a cabinet with climate control. The eggs that are to be incubated are placed upright, with the air cell facing upwards, in racks in the cabinet. Furthermore, it is generally known that during incubation the eggs have to be turned at regular intervals, inter alia in order to prevent the embryos from sticking to the eggshell. Embryos which have stuck to the eggshell die during the incubation process. During incubation, the eggs are generally initially preincubated in a first cabinet (during which process the chicks do not yet emerge from the egg), and are then placed in a second cabinet in order ultimately to be hatched therein (with the chicks emerging from the egg). The first and second cabinets may be the same cabinet, but in practice are often different cabinets, in which case the eggs are then transferred between the cabinets.
The first industrial large-scale incubation devices reached the market during the period from 1940-1960. In some countries, such devices are still in use. These are what are known as drum incubation machines. The racks of eggs in these drum incubation machines form part of the machine. Each rack contains a number of trays, on each of which eggs are situated. The trays are in this case fixed to the rack. The turning is carried out by tilting the entire rack. The vertical distance between trays located above one another within a rack in this case remains unchanged.
From about 1970, a development occurred according to which trolleys having a stack of trays holding eggs on each trolley are moved into the incubation device, in particular a chamber of the incubation device. Each trolley in this case comprises a frame on wheels or castors or other guides. Each frame in this case has a multiplicity of trays positioned above one another. Each tray has a multiplicity of egg positions. In this case, the turing is not effected by tilting the entire frame/trolley, but rather by tilting the trays about a horizontal axis with respect to the frame/trolley. The trays are each tilted from a first position to a second position. The first position and the second position are in this case complementary to one another, i.e. in the first position the angle of the tray with respect to the horizontal plane is −β degrees, and in the second position the angle of the tray with respect to the horizontal plane is +β degrees. During pivoting, therefore, the pivot angle is 2×β degrees. Specialists in the field therefore refer to a turning angle of β degrees. In the prior art, β is set to a fixed, invariable value, generally in the range from 38 to 45 degrees. When turning is being carried out in a hatching device with hatching trolleys of this type, it is observed that during tuning the vertical distance between trays positioned above one another changes. This distance is at a maximum at 0°, i.e. with horizontally positioned trays, and this distance is at a minimum in the first and second positions.
In the prior art and also according to the invention, the turning is carried out periodically. This turning generally takes place once every hour; however, according to the invention it can also take place at a lower or higher frequency.
In a system having trolleys which are moved into the incubation machine, it is also known to weigh the eggs in one single tray and to monitor the weight loss of the eggs during incubation on this basis. This weight loss occurs because during incubation the eggs evaporate (sweat) moisture and release gases. During incubation, in this known method the weight loss is monitored and the weight loss is influenced by controlling the relative humidity, the ventilation rates and the CO2 content of the air passed through the cabinet. Therefore, in the known method and device, the incubation is optimized by virtue of aiming to realize a weight loss of approximately 12% at a predetermined finishing time.
Although this known method does permit some optimization, in so far as the aim is an overall weight loss of approximately 12%, this method nevertheless does not permit accurate precision control and also, for example, does not make it possible to take into account the fact that not all the eggs in a batch of eggs to be hatched in a cabinet are identical. The quality of eggs generally differs from stack to stack. Furthermore, the incubation process does not take place identically at all positions in the chamber. In the known method, as has been stated, the relative atmospheric humidity, the ventilation rate and the CO2 level are acted on to enable the weight loss to be controlled. This process is identical for all the plurality of stacks in a cabinet.